Fabrication of ZnWO4 nanofibers by a high direct voltage electrospinning process

Mixtures of zinc acetate dihydrate, ammonium metatungstate hydrate, and 5 wt%, 6 wt%, and 7 wt% of poly (vinyl alcohol) (PVA) were electrospun by a + 15 kV direct voltage to produce fibers. In the present research, the electrospun fibers of 6 wt% PVA were further calcined at 400-600 degrees C for 3 h. The sanmartinite monoclinic structured ZnWO4 was detected by X-ray diffractometer (XRD) and selected area electron diffraction (SAED), weight loss by thermogravimetric analyser (TGA), morphology and particle size by scanning and transmission electron microscopes (SEM, TEM) and atomic force microscope (AFM), including their vibration modes by Fourier transform infrared spectrometer (FTIR) and Raman spectrometer. The 4.42 eV direct energy gap (E-g) and 460nm emission wavelength, caused by the electronic transition of (WO6)(2-) octahedrons, were determined by UV-visible absorption and photoluminescence (PL) spectrometers. A possible formation mechanism of ZnWO4 nanofibers was also proposed according to the experimental results. (C) 2011 Elsevier B.V. All rights reserved.